In the anime

In the Dare da? for the Japanese version of The Bug Stops Here, Jessie turns out to be the subject, cosplaying as a Venomoth. When the "Pokémon" was revealed, the narrator says "Venomoth", but the children shout "Incorrect!"

In the manga

In the Pokémon RéBURST manga

While Cosplay doesn't officially appear in most Pokémon manga, there is a technique based off Pokémon Cosplay in the Pokémon RéBURST manga called Burst. Unlike usual Pokémon Cosplay, the Burst techniques are used for battle purposes.

Pokémon.com

When it was relaunched in January 2010, Pokémon.com added a Pokémon Trainer Club, where players play games and earn coins to buy clothing at a Trainer store, some of which are Pokémon costumes.

In the fandom

Like most anime, manga and video game fandoms, cosplay is common within the Pokémon fandom. Most fans will dress up as human characters from the games and anime such as Ash, Team Rocket, female generational protagonists Misty, May, or Dawn, Officer Jenny or Nurse Joy. Many females crossplay as either Ash or James because of their youthful male looks, commonly known in Japan as bishounen, or "bishie" for short in the USA. Still, it is far from unheard of for fans to dress up in costumes of their favorite Pokémon species, especially if it is in the kigurumi or gijinka style of cosplay. Kigurumi is basically a hooded coverall pajama jumpsuit disguise of a character like Pikachu, while a Gijinka (also called "Moe anthropomorphism") is a human form of a species. Because of the popularity of Pikachu as the mascot of the Pokémon franchise, many young women dress in a Sweet Lolita style of dress at conventions.

Controversy

Cosplayers who dress up like Pokémon are sometimes targeted as being furries, which have been the center of many controversies. However, while there is undoubtedly overlap, Pokémon cosplayers and furries are not one and the same; there are Pokémon cosplayers who are simply Pokémon fans and not interested in the furry fandom, and there are furries who would never want to wear a Pikachu costume.